x86/uv: Implement UV BAU runtime enable and disable control via /proc/sgi_uv/

This patch enables the BAU to be turned on or off dynamically.

  echo "on"  > /proc/sgi_uv/ptc_statistics
  echo "off" > /proc/sgi_uv/ptc_statistics

The system may be booted with or without the nobau option.

Whether the system currently has the BAU off can be seen in
the /proc file -- normally with the baustats script.
Each cpu will have a 1 in the bauoff field if the BAU was turned
off, so baustats will give a count of cpus that have it off.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Link: http://lkml.kernel.org/r/20120622131330.GB31884@sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/include/asm/uv/uv_bau.h b/arch/x86/include/asm/uv/uv_bau.h
index 6149b476d9df..847c00b721b2 100644
--- a/arch/x86/include/asm/uv/uv_bau.h
+++ b/arch/x86/include/asm/uv/uv_bau.h
@@ -520,6 +520,7 @@ struct ptc_stats {
         unsigned long   s_uv2_wars;             /* uv2 workaround, perm. busy */
         unsigned long   s_uv2_wars_hw;          /* uv2 workaround, hiwater */
         unsigned long   s_uv2_war_waits;        /* uv2 workaround, long waits */
+        unsigned long   s_enters;               /* entries to the driver */
         /* destination statistics */
         unsigned long   d_alltlb;               /* times all tlb's on this
                                                    cpu were flushed */
@@ -586,6 +587,7 @@ struct bau_control {
         int                     timeout_tries;
         int                     ipi_attempts;
         int                     conseccompletes;
+        short                   nobau;
         int                     baudisabled;
         int                     set_bau_off;
         short                   cpu;